In the final draft script of "The Xindi", Hayes (and three MACO men with him) was described as "accustomed to a more formal, chivalrous atmosphere" than that aboard Enterprise, prior to joining the ship.

In December of that year, Hayes proposed a series of tactical drills be held for Enterprise's senior officers, a request which Archer agreed with. This caused a certain amount of friction between Hayes and Lieutenant Reed, who felt that Hayes was circumventing his authority by taking his request directly to the captain. This tension eventually came to a head when what started out as a simple sparring match between the two degraded into an all-out brawl in the corridors of the ship. The two combatants were forced to terminate the fight, however, when a hostile alien attempted to destroy the ship. Hayes and Reed were forced to work together to stop the alien, eventually succeeding in saving Enterprise. Later, in Captain Archer's ready room, the two of them were berated by Archer for the fight, and ordered to settle their differences immediately. The two complied, claiming that the dispute was settled. (ENT: "Harbinger")

The tension between the two resurfaced only a month later, however, when Archer, who was under the influence of a unique neurochemical, relieved T'Pol and Reed of duty and placed MACOs in command of Enterprise. As Archer was being influenced to sacrifice a majority of the ship's antimatter in order to restore power to a Xindi-Insectoidhatchery, the Enterprise senior officers were forced to retake the ship from the MACOs. This resulted in a firefight being fought on the bridge, with Hayes and Reed competing for control of the ship. Ultimately, however, the Starfleet officers were successful in taking control, and relieved the MACOs of duty. After Archer had been treated by DoctorPhlox, Reed conversed with Hayes about recent events, with Hayes admitting that respecting the chain of command was not as simple as he had once believed. (ENT: "Hatchery")

Hayes on his deathbed

In February 2154, Hayes led a boarding party aboard a Xindi-Reptilian warship to rescue Hoshi Sato, who had been abducted by the Reptilians. While the rescue mission was ultimately successful, and Sato was safely retrieved, Hayes was shot through the chest by a Xindi particle weapon mid-transport, suffering serious injuries. In Enterprise's sickbay, Hayes recommended that Reed should rely on CorporalMcKenzie and make use of her familiarity with the MACO team upon his death. Immediately thereafter, Hayes lost consciousness and, despite attempts by Dr. Phlox to revive him with cardiostimulators, Hayes succumbed to his injuries and died. (ENT: "Countdown")

Hayes was played by actor Steven Culp. He once speculated that Hayes' first name was either "Jeremiah" or "Jay". [1](X)

Finding Hayes' mindset was at first difficult for Steven Culp. "It was sketchy at first," he related. "There wasn’t a lot on the page and I know that the second episode I did, I was kind of like 'why am I here?' Because he didn’t have much to say, but I took that as my clue. Man of few words – man of action. It was kind of an experiment with me, almost like a David Mamet kind of character. Someone who is totally defined by his actions." [2]

An insightful article was influential in the development of Hayes. "Around the second episode I worked on, titled 'The Shipment', I came across this article in the [Los Angeles] Times," recalled Steven Culp. "It was about this young soldier in Iraq who had grown up in a bad neighborhood, grew up kind of a troubled kid who found himself in the military. He seemed like this dedicated, gung-ho soldier who had found fulfillment in the military. I took it to the director [of the episode] and said, 'This is me. This is my character.' It grew from there." (Star Trek: Communicator issue 151, pp. 43-44)